^ It's absurd to say there's no such thing as a common interest. I mean, the whole reason you are arguing for free market capitalism in the first place is because you think it is best for everybody.

The only thing that's absurd is you pretending to actually speak for anyone but yourself. You do not have any true insight into what "everybody" else wants. Because there is no collective, and you are not a part of it. There are only a whole bunch of different people with individual interests.

That aside, obviously if my interests happen to coincide with yours, then we can collaborate or engage in mutually beneficial trade. If our interests do not coincide, then we can chose to ignore each other. Our so-called "common interests" end as soon as either of us is no longer a willing participant. The same principle extends to society at large.